An imaging system typically includes an input imaging device that generates image information, and an output imaging device that forms a visible representation of an image based on the image information. In a medical imaging system, for example, the input imaging device may include a diagnostic device, such as a magnetic resonance (MR), computed tomography (CT), conventional radiography (X-ray), or ultrasound device. Alternatively, the input imaging device may include a user interface device, such as a keypad, mouse, or trackball, which is also capable of generating medical image information. As a further alternative, the input imaging device may include an image archival workstation for retrieving archived image information. The output imaging device in a medical imaging system typically includes a digital laser imager. The laser imager exposes an imaging media in response to the image information to form the visible representation.
The image information generated by the input imaging device includes image data containing digital image values representative of the image, and imaging requests specifying operations to be performed by the laser imager. Each of the digital image values corresponds to one of a plurality of pixels in the original image, and represents an optical density associated with the respective pixel. In response to an imaging request, the laser imager converts the digital image values to generate laser drive values used to modulate the intensity of a scanning laser. The laser drive values are calculated to produce exposure levels, on the imaging media, necessary to reproduce the optical densities associated with the pixels in the original image when the media is developed, either by wet chemical processing or dry thermal processing. The laser imager may perform a number of additional operations in response to the imaging requests generated by the input imaging device. For example, the laser imager may manipulate the image data, prior to generating the laser drive values, to produce a variety of different format and/or appearance characteristics.
The image information processed by the laser imager has a format determined by an input protocol associated with the particular input imaging device. Medical imaging systems typically are capable of handling image information generated according to a variety of diverse input protocols. An input protocol can be characterized as including a network driver protocol, which provides lower-level communications specifications as to a particular input imaging device, and a network interpreter protocol, which determines the format for interpreting image information generated by the input imaging device. The number of different input protocols results, to some degree, from the various types of input imaging devices presently in use, e.g., a magnetic resonance (MR), computed tomography (CT), conventional radiography (X-ray), or ultrasound device, each of which may generate image information according to a different protocol. The primary source of different input protocols is, however, the existence of a number of modalities, i.e., input imaging devices made by different manufacturers and having unique, manufacturer-specific input protocols. For example, manufacturers such as Siemens, Toshiba, GE, and Picker presently make CT-type input imaging devices that provide similar functionality, but which generate image information according to different modality-specific input protocols.
In addition to the ability to handle multiple input protocols, medical imaging systems typically are capable of handling communication of image information to output imaging devices according to multiple output protocols. Like an input protocol, an output protocol can be characterized as including an output driver protocol, which determines requirements for communication with a particular output imaging device, and an output interpreter protocol, which determines the format for translating image information into a form understood by the output imaging device. Different output protocols primarily result from the availability of laser imaging output devices having different sets of functional capabilities. The different sets of functional capabilities present varying complexity that can lead to different output protocols. For example, Imation Enterprise Corp. ("Imation"), of Oakdale, Minn., presently offers laser imagers having different sets of functional capabilities referred to as the "831," "952," and "SuperSet" sets, each of which is associated with a set-specific output protocol.
Existing medical imaging systems presently accommodate multiple input and output protocols on an ad-hoc basis by the design of point-to-point hardware and/or software interfaces specifically configured for a particular input protocol and a particular output protocol. The use of a custom-made interface is extremely inflexible. If communication with a different input imaging device is later required, the entire interface must be redesigned to handle the relationship between the new input protocol and the old output protocol. A change in the output imaging device similarly requires redesign of the interface to handle the relationship between the new output protocol and the old input protocol. Unfortunately, redesign of the interface is a cumbersome task that often requires a significant investment in hardware and/or software development time. Even seemingly minor modifications in functionality of an input or output imaging device can produce numerous, costly design changes that propagate throughout the interface.
One solution to these problems is described in parent U.S. Pat. No. 5,630,101, entitled "System for Communication of Image Information Between Multiple-Protocol Imaging Device." The system described in this patent application adopts an object-oriented, modular design in effecting a software-based direct-connect architecture to allow for significant flexibility in laser imager communication. An interface executive instantiates the needed input driver-input interpreter pair and the needed output interpreter-output driver pair to create a pipeline so that a particular host modality can communicate with a particular laser imager. Each of the input driver, input interpreter, output interpreter and output driver components is a discrete software object, or "black box." In this manner, each can be modified or replaced by a new object without affecting the performance of the others, or the overall pipeline. For example, the input interpreter and driver pair may be specific to a Siemens host modality, while the output interpreter and output driver pair may be specific to an Imation laser imager using the 831 protocol. If the latter pair is replaced with a pair specific to an Imation laser imager using the SuperSet protocol, the design of the components is such that the input interpreter and driver pair does not also need to be replaced.
Although the 5,630,101 patent promotes flexibility in laser imager architecture, it discloses only a direct-connect, point-to-point architecture. For every input-output pair, the interface executive must instantiate a separate input driver-input interpreter pair and output interpreter-output driver pair. That is, the interface executive must create a separate pipeline between each host modality and each laser imager. Although not a misgiving in a system having a relatively small number of host modalities, this can pose a problem in environments where a significant number of host modalities communicate with a plurality of different laser imagers. This is especially true in a networking environment, in which typically a number of network clients all speak the same protocol. In such a situation, it is desirable not to have redundant a input driver-input interpreter pair for each and every client. Besides the drainage in resources, this architecture also places excessive overhead on the interface executive.
Thus, there is an increasing demand for even more flexible medical imaging systems capable of providing communication between a variety of input and output imaging devices having multiple protocols. It is desirable that such medical imaging systems not only provide flexibility with respect to current protocols, but also be capable of adaptation to handle future protocols in a cost-effective manner. There also are increasing demands for network communication of image information between input and output imaging devices. In the medical imaging field, for example, the American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) have formed a joint committee to develop a standard for digital imaging and communications in medicine, known as the DICOM protocol. The DICOM protocol was designed to facilitate connectivity among equipment in the medical industry, particularly in view of the movement of hospitals from point-to-point environments to network environments. Medical equipment manufacturers throughout the industry are now beginning to implement the DICOM communications protocol. The DICOM protocol sets one standard for network communication of image information. However, other network protocols exist and will continue to be created. Thus, protocol translation continues to be necessary in network systems. The need for protocol translation in network systems creates problems similar to those encountered with point-to-point systems. Specifically, flexibility and ease of adaptation for multiple protocols continue to be of concern. Accordingly, there is a need for a system capable of providing network communication of image information between imaging devices according to multiple communication protocols.